侧脑室微量注射血管紧张素Ⅱ对大鼠中脑导水管周围灰质伤害性神经元电活动的影响

The Effect of Intracerebroventricular Injection of Angiotensin Ⅱ on the Electrical Activity of the Nociceptive Neurones in the Rat's Periaqueductal Gray

本实验用玻璃微电极记录技术，在５５只雄性ＳＤ大鼠ＰＡＧ区记录到６５个伤害性神经元，观察了 ＡＩＩ对 ＰＡＧ伤害性神经元电活动以及吗啡镇痛效应的影响。结果显示：①ＡＩＩ（５０ｎｇ、１μｇ、２μｇ／５μｌ，ｉ．ｃ．ｖ．）对ＰＡＧ区痛兴奋神经元（ＰＥＮ）电活动产生显著的兴奋效应；②９个ＰＡＧ痛抑制神经元（ＰＩＮ）在给 ＡＩＩ后 ８个产生抑制效应，一个无反应；③ＡＩＩ（５０ｎｇ、２μｇ／５μｇ，ｉ． ｃ． ｖ）部分翻转吗啡（ｉ．ｐ，２．５ｍｇ／ｋｇ体重）的抑制作用，两组间ＡＩＩ的作用有显著性差异。以上结果提示：ＡＩＩ可能通过易化ＰＡＧ区 ＰＥＮ、抑制 ＰＩＮ的电活动，从而调制伤害性信息的传递，拮抗吗啡镇痛。

65 nociceptive neurones in the PAG of 55 male SD rats were recorded by glass microprobe tech- nique. The effects of angiotensin Ⅱ (AII) on the electrical activity of nociceptive neurones in PAG and on the antinociceptive effect of morphine were observed. The results are as follows: (1)The injection of AII (50ng/5μl.1μg/5μ1. 2 μg /5μl, i. c. v. ) produced striking excitatory effect both on nociceptive dis- charges and spontaneous discharges of PEN in PAG; (2) In 9 pain inhibitory neurones(PIN), the elec- trical activity of & units was inhibited after the i. c. v. injection of All, and the electrical activity of 1 unit kept unchanged; (3) I. C. V. injection of AII(50ng, 2μg/5μl)partly reversed the inhibitory effect of morphine (i. p., 2. 5mg/kg weight) on the PEN in. PAG. The above results suggest that modula- tion of AII on the transmission of nociceptive messages and antagonism on the antinociceptive function of morphine may be completed by facilitating PEN and inhibiting PIN in PAG.